<!DOCTYPE html>
<head>
    <title>
        11
    </title>
<script src="vue.js"></script>
</head>
<body>
<div id = "app">
    {{ m }}
    <!-- {{ n }} -->
</div>
<script type="text/javascript">
    var data = { m : 111 };
    var vm = new Vue({
        el : "#app",
        data : data,
        // data : { m : 123 }
    }); 
    vm.$watch('m', function(newVal, oldVal){
        console.log('value change from',newVal,2, oldVal)
    })
    
    vm.m = 'test'


</script>
</body>
